Yaesu FT-991, Operating Manual

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Page 43 FT-991 O
peraTing
M
anual
d
igitAl
notch F
ilter
(
dnF
)
o
perAtion
The Digital NOTCH Filter (DNF) is an effective beat-canceling filter that can null out a number of interfering beat notes
inside the receiver passband. Because this is an Auto-Notch feature, there is no adjustment knob associated with this fil -
ter.
A
dvice
:
If a very strong interfering carrier is encountered, we recommend you first use the IF NOTCH filter, as it is the most ef -
fective notching tool in the receiver section.
1. Press the F(M-LIST) button, then touch [ DNF
] on
the LCD. The “ DNF ” will appear in the display.
To disable the Digital NOTCH Filter, just repeat the
above procedure, touching [ DNF
] on the LCD to choose
“
OFF
”. The “ DNF ” will turn off, confirming that the
Digital NOTCH Filter is not active.
d
igitAl
n
oiSe
r
eduction
(
dnr
)
o
perAtion
The Digital Noise Reduction (DNR) system is designed to reduce the level of random noise found on the HF and 50
MHz bands, and it is especially effective during SSB operation. By setting the Menu item “
110 DNR LEVEL
”, any of 15
different noise-reduction algorithms can be selected; each of these algorithms was created for dealing with a different
noise profile. You will want to experiment with the DNR system to find the best setting corresponding to the noise cur -
rently being experienced.
1. Press the F(M-LIST) button, then touch [ DNR
] on
the LCD. The “ DNR ” will appear in the display.
To disable the DNR system, just repeat the above proce-
dure, touching [ DNR
] on the LCD to choose “
OFF
”. The
“ DNR ” will turn off, confirming that the DNR system is
not active.
i
nTerferenCe
r
eJeCTion
F(M-LIST) Button
F(M-LIST) Button